Devices for riveting sheet metal employing rivet retainers and bucking tools are well known in the art. Generally, these devices have means for retaining the metal parts in a predetermined position and for drilling a hole in the exact location through which a rivet will be placed. The hole may be countersunk so that the head may be flush with the surface of the part. Further, these devices have the rivet retainer and bucking tool located on opposite sides of the parts to be joined, which tools are pressed against the parts to assure a secure relation while the rivet is pressed.
The prior art discloses a rivet retainer and bucking tool located at the ends of arms, which arms serve to form an elongate space therebetween to receive elongate members of the parts being joined. An example of these devices is disclosed in U.S. Pat. No. 303,968 to Allen, which discloses a structure for performing riveting operations at the interior of large sheet metal parts.
Because rivets necessarily are fastened in a position normal to the surface of the parts being joined, parts having contoured surfaces require riveting devices providing means for the retainer and bucking tool to be rotated so that parts can be received and retained of the proper orientation, allowing riveting operations to be performed thereon. In particular, the prior art contemplates devices having their radius of rotation colinear with the rivet axis so that the riveting tools can receive horizontal sheet metal in its raised position, and vertical sheet metal in its lowered position. A device of this type is disclosed in U.S. Pat. No. 1,507,958 to Hansen, et al.
Similarly, the prior art contemplates retainer and bucking tools being rotatable about an axis of rotation located through the middle of the bucking tool to permit variable rivet angles in workpieces having large radii of curvature. An example of this type of device is disclosed in U.S. Pat. No. 3,534,896 to Speller, et al.
The variable angle riveters of the prior art require that the workpiece be mounted on a variable angle platform to permit rivets to be inserted at various angles. These platforms have the disadvantages of slippage of the workpiece during operation, requiring precise adjustment between riveting operations to assure the proper placement of successive rivets. Consequently, a need exists in the art for a variable angle riveter where successive rivets may be inserted at a desired position on a contoured surface without altering the angle of inclination of the part between riveting operations and to permit the part to be located on a horizontal platform to avoid the danger of part slippage. This need for a variable angle riveter which requires minimum adjustment of the workpiece between successive riveting steps is particularly felt in industries where workpieces are excessively large, heavy, or are otherwise difficult or cumbersome to handle.
A further need exists in the art for a riveting device which is capable of inserting rivets at varying positions on a contoured surface without major adjustment of the relation between the part and riveter. Yet a further need exists for a riveter of sufficient size to receive and rivet tubular parts having a diameter in excess of about 8 feet. In particular, a need exists in the aircraft industry for a riveter which can receive and rivet fuselage sections having variable compound surfaces and diameters in excess of 12 feet.
The variable angle riveters of the prior art also suffer the disadvantage of placing the workpiece and riveting tools in a position where the operator can not directly view the riveting operation. The prior art riveting devices require a two step process whereby the operator sights the proper location for the drilling step and then moves to a remote location to operate the machine. Consequently, a need exists for a variable angle riveter that permits riveting operations to be performed within the view of the operator.